A new study, published in the European Journal of Preventive Cardiology, a journal of the European Society of Cardiology (ESC).1, found that drinking tea at least three times a week is linked to a longer and healthier life.
Dr. Xinyan Wang, Chinese Academy of Medical Sciences, Beijing, and the first author of the study, said: "Habitual tea consumption is associated with lower risks of cardiovascular disease and all-cause death. The favourable health effects are the most robust for green tea and for long-term habitual tea drinkers."
Lesser risk of cardiovascular disease
The researchers analysed data of 100,902 participants of the China-PAR project2 with no history of heart attack, stroke, or cancer. The experts had classified the participants into two groups: habitual tea drinkers (three or more times a week) and never or non-habitual tea drinkers (less than three times a week) and followed-up for a period of 7.3 years.
According to the study, 50-year-old habitual tea drinkers would develop coronary heart disease and stroke 1.41 years later and live 1.26 years longer than those who never or seldom drank tea. When compared with never or non-habitual tea drinkers, the analysis showed that habitual tea consumers had a 20% lesser risk of incident heart disease and stroke, 22% lower risk of fatal heart disease and stroke, and 15% decreased risk of all-cause death.
Potential influence of changes in tea drinking
The researchers also analysed the potential influence of changes in tea drinking behaviour in a subset of 14,081 participants with assessments at two time points. The average duration between the two surveys was 8.2 years, and the median follow-up after the second survey was 5.3 years.
The researchers said that the habitual tea drinkers, who managed to maintain their habit in both the surveys, had 39% lower risk of incident heart disease and stroke, 56% lower risk of fatal heart disease and stroke, and 29% decreased risk of all-cause death in comparison to consistent never or non-habitual tea drinkers.
Senior author Dr. Dongfeng Gu, Chinese Academy of Medical Sciences, said: "The protective effects of tea were most pronounced among the consistent habitual tea drinking group. Mechanism studies have suggested that the main bioactive compounds in tea, namely polyphenols, are not stored in the body long-term. Thus, frequent tea intake over an extended period may be necessary for the cardioprotective effect."
Analysis of types of tea
In addition, the researchers also analysed the type of tea to have a better understanding of the study. They said that drinking green tea was linked with approximately 25% lower risks for incident heart disease and stroke, fatal heart disease and stroke, and all-cause death. However, no significant associations were observed for black tea.
Dr. Gu said that the clear preference for green tea is extremely unique to East Asia. "In our study population, 49% of habitual tea drinkers consumed green tea most frequently, while only 8% preferred black tea. The small proportion of habitual black tea drinkers might make it more difficult to observe robust associations, but our findings hint at a differential effect between tea types," Dr. Gu added.
The researchers said that green tea is a rich source of polyphenols that eventually protect against cardiovascular disease and its risk factors including high blood pressure and dyslipidaemia. On the contrary, black tea is fully fermented and during this process polyphenols are oxidised into pigments and may lose their antioxidant effects. They also suggested that as black tea is often served with milk, it may counteract the favourable health effects of tea on vascular function.
